gno.land/r/moul/x/daily/bidimapdemo/v0⧉

1// Package bidimapdemo is a small gnoweb demo of the bidirectional map provided2// by the [p/moul/x/daily/bidimap](/p/moul/x/daily/bidimap/v0) library: it shows3// the reverse lookup and what happens when a binding is displaced.4//5// It contains no map logic of its own. Stateless, so Render is deterministic —6// which is precisely what the library is for.7package bidimapdemo89import (10	"strconv"11	"strings"1213	"gno.land/p/moul/x/daily/bidimap/v0"14)1516// Render renders the demo for gnoweb.17func Render(path string) string {18	var b strings.Builder19	b.WriteString("# Bidirectional Map\n\n")20	b.WriteString("Unique in both directions, demoing the ")21	b.WriteString("[`p/moul/x/daily/bidimap`](/p/moul/x/daily/bidimap/v0) library.\n\n")2223	m := bidimap.New()24	m.Put("alice", "admin")25	m.Put("bob", "auditor")26	m.Put("carol", "treasurer")2728	b.WriteString("## Roles\n\n")29	b.WriteString(table(m))3031	b.WriteString("\n## Both directions are O(1)\n\n")32	v, _ := m.Get("bob")33	k, _ := m.GetKey("treasurer")34	b.WriteString("- `Get(\"bob\")` → `" + v + "`\n")35	b.WriteString("- `GetKey(\"treasurer\")` → `" + k + "` — the reverse index, not a scan\n\n")3637	b.WriteString("## Displacing a binding\n\n")38	b.WriteString("Both sides are unique, so giving `alice` the `auditor` role cannot ")39	b.WriteString("simply be written — `bob` already holds it, and `alice` already holds ")40	b.WriteString("`admin`. `Put` **replaces**, and reports what it displaced:\n\n")41	evicted, _ := m.Put("alice", "auditor")42	b.WriteString("| displaced key | displaced value |\n|---|---|\n")43	for _, p := range evicted {44		b.WriteString("| `" + p[0] + "` | `" + p[1] + "` |\n")45	}46	b.WriteString("\n" + table(m))47	b.WriteString("\n`bob` is now unassigned and the `admin` role is vacant — one call, ")48	b.WriteString("both indexes still agreeing.\n\n")4950	b.WriteString("## Refusing instead\n\n")51	b.WriteString("`PutUnique` makes the other choice: it declines rather than displace.\n\n")52	ok := m.PutUnique("dave", "auditor")53	b.WriteString("- `PutUnique(\"dave\", \"auditor\")` → `" + strconv.FormatBool(ok) + "` — the role is taken\n")54	ok = m.PutUnique("dave", "secretary")55	b.WriteString("- `PutUnique(\"dave\", \"secretary\")` → `" + strconv.FormatBool(ok) + "` — both sides free\n\n")56	b.WriteString(table(m))5758	b.WriteString("\n> Keys come back **sorted**, never in map order: gno map iteration ")59	b.WriteString("order is unspecified, and a page built from one can differ between ")60	b.WriteString("nodes — a consensus bug, not a cosmetic one.\n")61	return b.String()62}6364func table(m *bidimap.BiMap) string {65	var b strings.Builder66	b.WriteString("| person | role |\n|---|---|\n")67	m.Iterate(func(k, v string) bool {68		b.WriteString("| `" + k + "` | `" + v + "` |\n")69		return false70	})71	return b.String()72}73